ity and the speed of decision-making (extended abstract) Michael Mandler Department of Economics Royal Holloway College, University of London Egham, Surrey TW20 0EX United Kingdom We consider agents who choose by proceeding through an ordered list of criteria and give the lower bound on the number of criteria that are needed for an agent to make decisions that obey a given set of preference rankings. Agents with rational preferences can always use lists with the lower-bound number of criteria while any agent with nonrational preferences must on some domains use strictly more criteria. We preview some of the results in Mandler (2009) and explain in more detail the order-theoretic link between rationality and rapid decision-making.